Structure determination of a 4-pyrone from the liverwort Plagiochila bifaria (Sw.) Lindenb. (Plagiochilaceae)

Rycroft, D.S. (2008) Structure determination of a 4-pyrone from the liverwort Plagiochila bifaria (Sw.) Lindenb. (Plagiochilaceae). In: Mohamed, H., Baki, B.B., Nasrulhaq-Boyce, A. and Lee, P.K.Y. (eds.) Bryology in the New Millennium. University of Malaya: Kuala Lumpur, pp. 395-403.

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The centenary of the presentation in 1907 of the "polyketide" hypothesis by Collie, along with his use of a 4-pyrone as an example, is marked by reporting the discovery and isolation of 2-(3,4-dimethoxyphenethyl)-6-methyl-4-pyrone from <i>Plagiochila bifaria</i>. This compound dominates the phytochemical profile of the deuteriochloroform extract of a Venezuelan specimen of <i>P. bifaria</i> and the structure was determined using spectroscopic techniques, especially 2D NMR. This natural product is novel because it contains what appears to be the first example of a monocyclic 4-pyrone that has a polyketide origin. The hypothetical pathway for cyclization of a triketocarboxylic acid to a 4-pyrone was known to be applicable to model systems but no examples of natural products from this route were known. This compound is the same as one of a series of compounds observed previously in an extract of a Brazilian specimen of <i>P. bifaria</i>; the working structures that were proposed earlier require revision. The mass spectral characteristics are the same as those reported (parent and base peak) in 1987 for the major component observed in the GC-MS profile of an extract of a specimen of <i>P. bifaria</i> from Peru. The roles played by Birch and Robinson in the renaissance of the polyketide hypothesis almost fifty years after its initial launch are considered. Based on evidence from their publications, they worked independently of each other. It appears Robinson always had knowledge of Collie's hypothesis when developing ideas about structural relations of natural products whereas Birch initially was unaware of both Collie's and Robinson's ideas on the subject.

Item Type:Book Sections
Keywords:phytochemistry, polyketide biosynthesis
Glasgow Author(s) Enlighten ID:Rycroft, Dr David
Authors: Rycroft, D.S.
Subjects:Q Science > QK Botany
Q Science > QD Chemistry
College/School:College of Science and Engineering > School of Chemistry
Publisher:University of Malaya
Copyright Holders:Copyright © 2008 University of Malaya
First Published:First published in
Publisher Policy:Reproduced with permission of the publisher

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